Carbon: Study finds new method for customized air purification of toxic gases

WASHINGTON: Volatile organic compounds (VOCs) are found in everyday products such as paints, adhesives, furniture, cosmetics, and deodorants. Constant exposure, on the other hand, can result in major health issues such as respiratory sickness, headaches, rashes, and cancer.
Natural ventilation is the most effective technique to remove VOCs in interior air, but due to the frequency of extreme environmental conditions (e.g., high concentrations of fine dust, heat waves, and extreme cold), air purifiers have lately become a widespread strategy to preserve indoor air quality.
Air purifiers generally remove VOCs through adsorption with activated carbon, which has a non-polar carbon surface and a large specific surface area. This activated carbon is effective at removing non-polar compounds like toluene and benzene but not polar chemicals like ketones and aldehydes.
Dr Jiwon Lee and Dr Youngtak Oh from the Centre for Sustainable Environment Research have developed a new adsorbent technology that can efficiently adsorb amphiphilic VOCs, which have both hydrophilic and hydrophobic properties and are difficult to remove with existing activated carbon technology, according to the Korea Institute of Science and Technology (KIST, President Seok Jin Yoon).
The KIST research team created a graphene-iron oxide heterostructure by precisely regulating the surface oxidation of graphite and iron, resulting in a high adsorption capacity for amphiphilic VOCs due to the increased surface oxygen functional groups and iron oxide. This novel adsorbent outperformed traditional activated carbon adsorbents in the adsorption of amphiphilic VOCs by up to 15 times.
They also found that precise oxygen functional groups and iron oxide control of the adsorbent can offer flexible surface optimization freedom for the desirable nature of the pollutant. By testing four different ketones that are difficult to control with activated carbon adsorbents, the researchers found the correlation between the length of carbon chains and the adsorption efficiency; by optimizing the content of oxygen functional groups and iron oxides in the adsorbent, they were able to bring the maximum removal efficiency for the ketones.
The researchers also analyzed the sub-nanometer electron transfer phenomenon between the adsorbent and VOC molecules; they found a link between the geometric shape of the pollutant and its adsorption trend for the first time. This is expected to enable the development of customized detection and control technologies for various air pollutants in our environment.
“Unlike previous studies that focused on the mere improvement of the adsorption performance and regeneration efficiency of adsorbents, we succeeded in developing a breakthrough material that exceeds the limits of existing adsorbents using accessible materials such as graphite and iron, which have high commercialization potential,” said Dr Jiwon Lee.